Re: Sailing with a tide or current

What I mean is that the time/effort to plane has nothing do do with the
direction of current per se, presuming the current is constant. The
view that it does is called the Lee Bow Effect and it is a debunked and
faulty belief that proclaims that a boat will encounter different
apparent wind speeds and sail power depending on the angle of the
current from tack to tack (since the wind is never constant, either in
direction or speed but the current usually is during the window of time
considered.) Racing sailors used to think (many still do) that a
current pushing on the lee bow allows the driver to pinch on that tack
by assuming that there is a resultant apparent wind "lift" and velocity
increase. This as opposed to sailing in a current "hitting" the
windward side of the boat. Here's a link to the discussion:
http://www.ussailing.org/member/library/wiodcurrent.htm

There are other factors that are caused by current, such as larger chop
created by surface friction when the wind opposes the current, or
standing waves that would exist differently (or not at all) if current
changed direction (like at Swell in the Gorge).

I sail in current a lot and agree that chop makes a difference in the
ability to plane, but not always in a helpful way. And it is a
different question of whether the direction of the current changes the
ability to plane. The former is the effect of the wind blowing over
water with current, while the latter is the mythical lee bow effect.. A
four knot current with 15 knots of wind in the same direction will
combine to produce almost dead flat water.

We are speaking of traditional windsurfing venues, of course, not
Ho'okipa or even the Gorge on a 3.0 day in the spring. Those hydrolics
are very unique and make it almost impossible to gauge what is really
going on under the board at any particular time.

It's one thing to say that it's easier to plane up in flat water, quite
another to live with the consequences of trying maintain position
relative to a fixed point (ie, staying upwind). In contrast sometimes
oncoming chop allows the sailor to use the chop to plane up at a higher
angle relative to the true wind on one tack when the other tack offers
chop in a slightly different angle relative to the true wind. This is
a phenomenon of planing and control that Cliff aludes to, I think, and
what you describe, John. Your example, John, works when everything
sets up at 90 degrees. Any slight deviation from this situation is the
context in which the debate surrounding the mythical lee bow effect
takes place, and is almost always the practical reality when
windsurfing.

I hope this clarifies my earlier statement.

-Dan




the principal wrote:
strange comment..

how can current NOT make a difference

it is extremely evident at 10 knots,

a wind of 10 knots in the same direction as current of 2 knots means
board and surfer see 8 knots on beam reach. HUGE difference and that
dosen't even include the rotational component on the tops of the small
waves at 10 knots. That leaves very little apparent wind no matter how
you slice and dice it.

Two methods lead to the same end result,

know your spot or work it out with vector diagrams. the result is the
same, current can mess with you, good wind opposes current and bad wind
with current.

But this....

nothing directly to do with
whether the current is favorable or foul.

Is very wrong,,, I'm surprised Dan said it and I think it may not be
reading correctly on the web.

Dan Weiss wrote:
Diff's in planing from tack to tack have nothing directly to do with
whether the current is favorable or foul. It can be that your own
technique is different from on tack to tack, your equipment is
different (sails are not perfectly symmetrical from tack to tack) and
your angle to the chop is probably different tack to tack.

Relative to a fixed point on land, a foul current can illuminate the
assymetry more than a favorable current because of the tendency to sail
at one's own limits to stay upwind. A current running upwind requires
less from the sailor to plane up and to stay upwind. That's one of the
reasons people sail much smaller boards in the Gorge than at other
places -even in the same wind.

One tip is to do everything you can to reduce assymetry, and get up to
a plane ASAP regardless of the angle required to be sailed. On a
shortboard in current, you go downwind so much faster spending a lot of
time off a plane. At least when planing you can be on your "bad" side
for less time and make the most upwind out of the time you are planing
rather than bobbing like a cork.

Another tip is to use lightly larger gear, particularly a larger fin.
You need power to point higher when the water flowing under your board
is at a lower speed when pointing compared to a static body or
favorable current. By current I mean at least 3 knots plus.

Finally, it sounds like you did the right thing by jamming upwind at
every chance, particulary on the "good" tack.

-Dan
Zephyr wrote:
Hey all,

Last weekend I had my first chance to sail in a situation where there
was a current in the water, most sailing I do is on small inland lakes
with no current. Well, I have gained respect for those of you who
sail with the current at your disadvantage. In my session the wind and
current were heading in the same direction. I was launching from an
area that had no current and would quickly plane up and power off.
however after a 1/2 mile run out I'd tack and head back in. I couldn't
for the life of me get back onto a plane. I had to pump like a dog to
get back up. Once closer to shore though, were the current was less,
I'd plane off like nobody's business.

Any tips or tricks to help in situations like this? After I figured
out that the wind wasn't constantly die-ing at the same spot I realized
what was happening and started to drive upwind on my "out" leg, and
then came out even on the run back in.

If I hadn't learned to pump I doubt I would have planed on the way back
in.

For those of you who can sail "downwind" all session, man, you are
fourtunate.


Dave

.

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